B2B with external users

I am looking at a solution where there are multiple Azure tenants, multiple PBI Tenants.

The user wants to implement B2B connections for Power BI (adding guests to the central AD Tenant with premium capacity)

I have been informed that the "Guest Users" will require Azure AD Premium licenses

Looking at

https://powerbi.microsoft.com/en-us/blog/power-bi-expands-access-to-intelligence-for-external-guest-users/

states

This new feature is the result of Power BI integration with Azure Active Directory (AD) business-to-business (B2B) collaboration.

which contains a link to Licensing guidance for Azure AD B2B collaboration

and states "With Azure Active Directory (Azure AD) business-to-business (B2B) collaboration, you can invite External Users (or "guest users") to use your paid Azure AD services. For each paid Azure AD license that you assign to a user, you can invite up to five guest users under the External User Allowance."

Is Power BI Classed as a "Paid Azure AD Service" in this case?

Where can I find clarification?

Regards

Andy